<!--
  Copyright 2020 The Chromium Authors. All rights reserved.
  Use of this source code is governed by a BSD-style license that can be
  found in the LICENSE file.
-->
<style>
  #hover:not(:hover) .show-on-hover {
    display: none;
  }
</style>
<div id="hover">
  <span>Some text, always shown</span>
  <span class="show-on-hover">Some text here, only shown on hover</span>
</div>
